Research — notes from behind the specification

These are notes from the measurements, written down close to the time the measurements were taken. They are not marketing copy, and they are not the test report itself: where a figure is quoted here, the testing page states the instrument, the method and the conditions behind it.

We publish them because a specification you are asked to believe is not much use. A specification you can read alongside the reasoning is.

Reports and notes, newest first. Where an entry is marked In progress, the method and the summary are on the site but the full tables and charts are not yet — we would rather mark it in progress than publish an unfinished report as if it were finished.

There are four routes by which swapping a cable can reach your ears. Anything a listing claims about a cable has to arrive through one of them.

1. Level, through the divider. Cable impedance and earphone impedance form a voltage divider, so a cable mostly changes how much signal arrives, and barely changes how the frequencies relate to each other. In the pairing we measured on 4 November 2026 — our own Purity CHP-12B against a reference earphone — that level loss was about 0.27 dB at 1 kHz, and the shift between frequencies stayed inside ±0.14 dB. Turn the volume up by the same amount and the balance is essentially where it was. The measurement behind that sentence — charts, the frequency-by-frequency table, and what it does not cover — is its own page: Does a cable change the sound? We measured it.

2. Contact resistance, and how stable it is. The interface between the two connectors is where a cable’s variability lives. A connector seated with a little play, a contaminated or worn socket, a latch that does not fully engage: each adds a resistance larger than the copper’s own, and worse, one that moves when you move. This is why the plating is specified, why we ask you to check fit before judging anything, and why a cable measured once at the bench is not the same claim as a cable measured after a year of plugging.

3. Fit, weight and stiffness — an acoustic route. A heavier or stiffer cable changes how an earphone hangs in the ear, and how an earphone hangs changes how the tip seals. Seal is an acoustic variable with a real effect on low-frequency response, and it outweighs every electrical effect a cable has. Cable weight, drag on the ear, microphonics (the rubbing of the cable transmitted through the earpiece), and whether the jacket keeps its flexibility in the cold all reach your ears by this route.

4. Time. Strain relief at the ear, the wear behaviour of the connector, resistance to kinking and to sweat — whether the cable still delivers routes 1 to 3 after a year of use.

What a cable does not do. It does not change the driver’s response beyond the divider effect in route 1. It does not change the acoustic chamber, the nozzle, a crossover or DSP, or a driver’s distortion behaviour. If somebody says a cable “opens up the soundstage”, they are either describing one of the four routes above in loose language, or they are not making a claim about sound.

We do not make claims we cannot attach a measurement to — and on a passive cable there is no measurement we could run that would support that phrasing.

If you swap a cable and hear a difference, one of the four routes explains it. Usually it is route 2 or route 3. That is a real difference and it is worth taking seriously; it is simply not a difference in how the cable “sounds”.

Two things are outstanding, and they are marked as pending wherever they touch a published figure:

• Re-measuring finished-cable resistance and the impedance curves on the production build, so that the numbers on the specification page belong to the product being sold. Until that is done, every finished-cable figure on this site is labelled as coming from a pre-production sample.
• Sample-to-sample spread across one build, since a single cable tells you nothing about the next one.

The impedance and frequency-response results themselves are no longer owed: the 4 November 2026 round is published as data with charts drawn from it in Does a cable change the sound? We measured it.